Moderately hypofractionated carbon ion radiotherapy for prostate cancer; a prospective observational study "GUNMA0702"

BackgroundCarbon ion Radiotherapy for prostate cancer is widely used, however reports are limited from single institute or short follow up. We performed a prospective observational study (GUNMA0702) to evaluate the feasibility and efficacy of carbon ion radiotherapy for localized and locally advanced prostate cancer.MethodsBetween June 2010 and August 2013, 304 patients with localized prostate cancer were treated, with a median follow-up duration of 60months. All patients received carbon ion radiotherapy with 57.6Gy (RBE) in 16 fractions over 4weeks. Hormonal therapy was given according to the risk group. Toxicity was reported according to the Common Toxicity Criteria for Adverse Event, Version 4.0 by the National Cancer Institute.ResultsThe overall 5-year biochemical relapse-free rate was 92.7%, with rates of 91.7, 93.4, and 92.0% in low-risk, intermediate-risk, and high-risk patients, respectively. The 5-year local control and overall survival rates were 98.4 and 96.6%, respectively. Acute grade 3 or greater toxicity was not observed. Late grade 2 and grade 3 genitourinary and gastrointestinal toxicity rates were 9 and 0.3%, and 0.3, and 0%, respectively.ConclusionsThe present protocol of carbon ion radiotherapy for prostate cancer provided low genitourinary and gastrointestinal toxicity with good biochemical control within 5years.Trial registrationUniversity Medical Information Network Clinical Trial Registry number: UMIN000003827.